They're going to have to seriously exaggerate Metallo's power if it takes Superman, Batman, Nightwing, Wonder Woman and Flash to take him down. Usually, Superman alone is able to take down Metallo. In the Public Enemies movie, it only took Batman and Superman to defeat Metallo. For this Metallo to work, he'd have to be a lot more powerful than he normally is.

I dunno how i feel about Bats, Nightwing, Superman, Wonder Woman and Flash all teaming up to only fight Metallo. For those characters to all team up, I'd think that a more powerful villain would be necessary